A Low-Emissivity glass refers to a glass in which a low emissivity layer containing a highly reflective metal in an infrared light region such as silver (Ag) is deposited as a thin film. Such a Low-Emissivity glass is a functional material having an energy saving effect of the buildings by reflecting a radiant light in the infrared light region to block an outdoor solar radiant heat in summer and to preserve an indoor heating radiant heat in winter.
Generally, since silver (Ag) used as the low emissivity layer is oxidized when being exposed in the air, an dielectric layer is deposited as an oxidation prevention layer on an upper part and a lower part of the low emissivity layer. Such a dielectric layer also functions to increase a visible light transmittance.